Apparatus for drying charges for shaft furnaces



May 15" v E. DIEPSCHLAG APPARATUS FOR DRYING CHARGES FOR SHAFT FURNACES Filed sent. 19. 1921 Patented May '15, 1923.

UNITED STATES PATENT. OFFICE.

y 'ERNST DIEI'SCHLAG, or BREs'L-AU, GERMANY.

APPARATUS FOR DRYING CHARGES FOR SHAFT FURIlACES.

Application filed Septembcr19, 192i. Serial No, 501,808.

. To it comer n:

Be it known thatI, ERNST DIEPSOHLAG, a citizen of the German State, residing at 25 Borsigstrasse, Breslau, Germany, have inventedcertain new and useful Improveinto the smelting or combustion zones of shaft furnaces (blast furnaces, gas producers) should be first prepared, for example, by drying.

Experience has demonstrated that for this purpose, it is unnecessary to provide special sources of heat, if, according to the invention, the preparatory drying of the material to be introduced be effected by means of the heat of the furnace gases, assisted where convenient by the direct or indirect action of some additional source of heat outside the furnace, I

In using the heat of the furnace gases at the mouth of the furnace, the material to be dried, consisting of fuel and ore in the case of blast. and like furnaces, or of fuel only in the case of gas generators or producers,

is introduced as part of the ordinary chargethrough feeding devicesfrom above into the mouth of the furnace in the usual way. Thereupon the coarser and finer particles f the charge are separated. The-finer particles are carried forward by the waste gases 'of the furnace through the waste gas outlet and flues and settle in the dust collectors provided for the cleansing of these gases. During their passage into the mouth of the furnace and away with the furnace gases, the fine particles are rendered completely dry While in suspension in the current of heated furnace gases, so that they are thus in a suitable condition to be fed into the smelting or combustion zone of the furnace.

By charging the furnace with the material to b dried in the manner described, the furnace or waste gases are cooled in taking up the moisture of the vsaid material and their subsequent cleansing is thereby facilifated.

If there should be any risk of disturbing the furnace by the charging of the finely grained smelting charge and fuel by reason of the presence of moisture therein, it is advisable to introduce this material into the furnace or waste gas flues. There of the waste gases.

If, for any reason, the ,object aimed at, namely, that of preparing the fuel and the they will be, completely dried by the heat ore which are to, be directly charged into the smelting or combustion zone of the furnace, is not attained or cannot be effectedby charging the material into the furnace or by the action of the furnace or waste gases in the manner hereinbefore described, then'the preparation of the material may be assisted or effected by the use of some outside source of heat or of waste-heat. Heat, for instance. may be obtained by supplying to a heating or drying apparatus into which the material to be dried is introduced, air

that has been preheated in air-heaters or other heat accumulators, or by directing upon the material a heated blast or current of air. Further additional sources of heat which may be considered for this purpose are the waste gases from air-heaters, from steam boilers, gas engines and metallurical furnaces (such as cupola-furnaces and artin furnaces or the like). These Waste gases have at the same time the advantage that, owing to their deficiency in oxygen, all oxidising effects on the material are avoided. The heated Waste gases may be Withdrawn from the Hues by fans or similar devices, in

the event of the heating and, drying plant for the material to be dried not being arranged directly between the furnaces or the. like and the corresponding chimneys or outlets.

In the case of furnaces supplied with compressed gas or compressed air, as, for instance, cupola furnaces, and also in the case of air heaters operated with compressed air, exhausters and chimneys may oe dispensed with.

These various means of efi'ectingfthedrying of the materialmay be applied both separately, or simultaneously together. In

drying the material other than by passing it into the furnace mouth with the charge as hereinbefore described, the material may be heated and dried either directly by causing thehea-ted gases to flow, in drum driers or the like, over it or by conducting it, in a finely divided current and in vertically disposed pipes, in a direction contrary to that of the current of waste or furnace gases,

or the operation may be carried out, indirectly, in apparatus. heated externally.

In the accompanying diagrammatic drawings two possible forms of drying apparatus adapted for carrying out the vinvention are diagrammatically represented, and in both of these constructions, the heat from the furnace or waste gas is used for pre-heating the material to be introduced into the smelting or combustion zone of the furnace.

Figure 1 is a sectional elevation of a construction of drying apparatus in whichthe heated waste gases pass directly in contact with the material to be dried.

Figure 2 isa similar sectional elevation of a. construction of dryer in which the heated' gases do not contact with the material to be dried.- I

In the apparatus illustrated in Fig. 1, thefurnace' or waste gases fiow through the pipe 1, andpass by way of the valve 13into a casing 14: into which projects the drying cylinder '2 provided with a rotating screw conveyor 3. The gases pass through the cylinder 2 and escape by Way of the valve 15. The materials to be dried are introducedinto the cylinder 2 at 4 and are carried forward by the conveyor 3 until they ,finally pass out of the drying cylinder at 5, where they are collectedin the casing 14,

' the lower part of which is formed as a hopper, and are thence introduced into the smelting olr combustion zone of the furnace. The pipe 6 serves as why-pass, its purpose being to render'it possible to cut out the gdrying cylinder 2 and the conveyor 3, for

example, in the case of repairs,.by closure of the valves 13, 15 and the opening of the valve 16. It is obviously of no importance that dust coming from the furnace "should settle in the drying cylinder 2, as it returns with the charge to the furnace.

In the 'event of the heat in the gases proving insufiicient, or if a further stage in the process of preparin the material should be required, for examp e, if a partial reduction is intended, it may be convenient to increase the temperature from an external source of Such an external source of heat is indicated in the apparatus represented in Fig. 1. The cylinder 2 is surrounded by a concentric casing 17 having a supply conduit 7 for the combustion gases evolved by a burner 8. The said gases traverse the casing 17 in the direction indicated by the arrows and escape again through an outlet pipe 9.

In order to prevent the formation 0 lumps of the material during drying, it. is advisable to fit a disintegrating device at the outlet from thedrying cylinder and in such manner that itis advantageously disposed in the current of gas, so that it too should be heated, for otherwise the material may easily cake. This device consists of the cylindrical grid 10 and grinding balls 11. The removal of the dust from drying drums is usually known to cause diflioulties, but the presence of dust in the present case is of no account, and does not constitute a nuisance for the reason hereinbefore described. Dust "is carried forward by the furnace gases, and is separated out in the operation of cleansing of the gases and is thus recovered.

The heat of the furnace or waste gases can also be utilized? indirectly without 9.0-

tual contact between the material and the gases.

Figure apparatus for this purpose. A drying cy inder 2 with screw conveyor 3 is built into v 2 illustrates an example of dryin naces comprising a chamber, a drying cylinder extending into the chamber, a conveyor in the drying cylinder for feeding forward the material, a disintegrator positioned in the chamber to receive the fuel from the drying cylinder and discharging the same into the chamber, and means for passing furnace waste gases through the chamber and drying cylinder to dry the fuel and heat the disintegrator.

ERNST DIEPSCHLAG. 

